Countersinking apparatus



Feb. 23, 1954 s. E. REES 2,669,887

COUNTERSINKING APPARATUS Filed Aug. 17, 1956 4 Sheets-Sheet l ATTOFF/VEKS Feb. 23, 1954 s, E, REES 2,669,887

COUNTERSINKING APPARATUS Filed Aug. 17, 1950 4 Sheets-Sheet 2J/zro/oJ//re E. Rees -r JNVENTOR.

BY 444A/ @Zd 2. ix/M16. ATTORNEYS Feb. 23, 1954 5, E, REES 2,669,887

COUNTERSINKING APPARATUS Filed Aug. 17, 1950 4 Sheets-Sheet 3 Feb. 23,1954 s. E. REES COUNTERSINKING APPARATUS 4 Sheets-Shet 4 Filed Aug. 17,1950 v jm n r I* IVY/infin! JropJ/nre E. Rees l INVENTOR.

j# A Troma/5 y;

Patented Feb. 23, 1954 COUN TERSIN KIN G- APPARATUS Shropshire E. Rees,Houston, Reed Roller Bit Company,

poration of Texas Tex., assignor to Houston, Tex., a cor- ApplicationAugust 17, 1950, Serial N o. 179,908

15 Claims.

This invention relates to new and useful irnprovements in countersinkingapparatus.

-One object of the invention is to provide an improved apparatus forcountersinking openings or holes in a plate, sheet or other member andwhich is particularly adaptable for use in accurately countersinkingopenings in aluminum plates or sheets employed in aircraft manufacture.

An important object of the invention is to provide an improvedpneumatically-operated apparatus having means for maintaining thecountersinking cutter in axial alignment with the opening beingcountersunk and also for accurately controlling the depth of thecountersinking operation.

Another object is to provide an improved countersinking apparatus havingmeans for 1ocating and locking the plate or member being Vcountersunk inproper position relative to the countersinking cutter, with said lockingmeans functioning to form a rigid support for the member during thecountersinking operation, whereby accuracy of the operation is assured.

A further object of the invention is to provide an apparatus of thecharacter described, wherein the countersinking tool or cutter ismechanically and automatically controlled and is engaged with and fedinto the work to perform the countersinking at a controlled rate offeed; the means for controlling the rate of feed being readilyadjustable to adapt the apparatus to any type of countersinkingoperation in accordance with the size of opening being countersunk andthe material being worked upon.

Still another object of the invention is to provide an improvedpneumatic tool for countersinking an opening in a plate member havingmeans engageable with the side of the member opposite that in which thecountersink is formed, whereby said means forms a backing or support forthe member during the countersinking operation; the engagement anddisengagement of said means being accomplished automatically and beingsynchronized with the movement and operation of the countersinking tool,whereby the countersinking operation may be accurately carried out in aminimum length of time.

A still further object is to provide an apparatus, of the characterdescribed, which includes an improved centering assembly for accuratelymaintaining the cutter in axial alignment throughout the countersinkingoperation; said centering assembly also functioning to control the rateof feed ofthe tool to the work, as well as the depth of cut of the tool,whereby the construction yoi' the tool is simplified.

A particular object is to provide an improved duplex piston arrangementfor an apparatus, of the character described, with one of the pistonsbeing connected to the locking means which engages and supports the workduring the countersinking operation and the second piston being securedto the countersinking tool; operation of the pistons and the coactiontherebetween controlling actuation of the locking means and movement ofthe tool in the necessary and desired sequence.

'I'he construction designed to carry out the invention will behereinafter described together with other features thereof.

The invention will be more readily understood from a reading of thefollowing specification and by reference to the accompanying drawingsforming a part thereof, wherein an example of the invention is shown,and wherein:

Figure 1 is a vertical sectional view of a. countersinking apparatus,constructed in accordance with the invention and illustrating the partsin a position at the beginning of the countersinking operation,

Figure 2 is a view similar to Figure 1 and illustrating the drivemechanism for imparting rotation to the cutter and showing the cutter ina position engaging the work and just prior to rotation,

Figure 3 is an enlarged vertical sectional view of the apparatus showingthe position of the parts at the completion of the countersinkingoperation,

Figure 4 is an enlarged sectional detail of the duplex pistonarrangement, with the pistons in position just prior to beginning thecountersinking operation,

Figure 5 is an enlarged sectional detail of the piston arrangement withthe pistons in a position just prior to final unlocking anddisengagement of the tool from the work,

Figure 6 is a partial elevation of the lower portion of the apparatusillustrating the centering yassembly and adjustment of the limitingmeans,

Figure 7 is an enlarged longitudinal sectional view of the lower portionof the guide member and showing the locking element in a retractedposition,

Figure 8 is a similar View with the locking element in expanded positionin engagement with the work piece,

Figure 9 is an enlarged horizontal cross-sectional view taken on theline 9-9 of Figure 7.

Figure is an isometric view of the locking element,

Figure 11 is a horizontal cross-sectional view taken on the line l l-I Ioi Figure 3,

Figure 12 is a horizontal cross-sectional view taken on the line l2-l2of Figure 3,

Figure 13 is a vertical sectional View taken on the line l3-I 3 ofFigure 12,

Figure 14 is a vertical sectional View taken on the line lfl-l i ofFigure 12,

Figure 15 is a vertical sectional view taken on the line l-lli of Figure12, and

Figure 16 is a diagrammatic view of the hydraulic system or" thecentering assembly.

In the drawings the num ral lll designatesa main housing or casing whichis generally cylindrical and which is formed with a bore Il and acounterbore l2, an annular shoulder i3 being pre-vided between the boreand counter-- bore. The upper end of, the housing has a cylinder itsecured. thereto and projecting upwardly therefrom, and it is preferablethat the cylinder have substantie.. the same externaly diameter as thehousing. The cylinder has a bore i5 which has its lower end closed by atransverse partition it and which. has its upper end closed by .asuitable cover plate l1 which. is bolted or otherwise secured inposition on they cylinder.

A- countersinking tool or cutter A is adapted to be mounted axiallywithin the housing, and, as will be explained, may undergo a rotativemovement with respect thereto. The cutter assembly, as shown in Figure3, inclu-:les a` tubular drive shaft if. which extends axially of thehous ing I3, and the upper end of the vdrive shaft is mounted in-suitable bearings l5 with the intermediate portion of the shaft beingmounted with in` bearings 2Q. The lower portion of the shaft i8 has theshank 2| of the countersinking cutter secured thereto. vThe upperportion of the drive shaft i8 extends through the bore Il ci the housingle while thelower portion projects downwardly through the counterborel2. A sleeve '22 surrounds the lower portion of the drive shari; andha-s its upper portion engaged within the counterbore I2; this sleeve isprovided with an external flange 23 which engages within an annularrecess 2d in the lower end of the housing and the flange is secured tothe housing by bolts 25.. The sleeve 22 thus forms a bearing for thelower portion of the drive shaft. External shoulders 26 and ill' areformed on the drive shaft adjacent the bearings IS and 2t whereby thedrive shaft is incapable of axial movement withrespect to the housingbut may be rotated relative thereto.

For imparting a rotation to the drive shaft' i8, a beveled gear 23 is`keyed to the upper portion of the drive shaft within the upper Vportionof the housing ill, and this gear is in constant mesh with a drivepinion 2S secured on the end of an operating shaft 3e. The drive 'shaft3G is mount ed in suitable bearings 3l located in onefend of a casing 3iwhich is secured within a. radial opening 33 formed in the housingl lil.The casing 32 is fastened by bolts 3c to the housing and said casing, asclearly shown in Figure .2, projects radially from one side of thehousing. This casing houses suitable pneumatic mechanism (not shown)which is air operated to impart rotation to the drive pinion 29. An airconduit 35 has connection with the casing and a suitable control lever33 controls actuationv of theipneumatic drive mechanism to controlrotation of the drive pinion 29. y

It will be evident that when the pneumatic drive mechanism is operatedby means of the control lever 36, the pinion 29 is rotated and throughits engagement with the gear 2B a rotation is imparted to the driveshaft i3. Because the countersinking cutter A is secured to the lowerend of the drive shaft it will be obvious that rotation of the driveshaft, will impart a rotation to the cutter. Thus, when the cutter isengaged with a plate member or work piece B and subsequently rotated, acountersinking operation will be performed on the upper portion of anopening C (Figure 3) which extendsy through said plate4 member or workpiece.

`In the countersinking o an opening such as C which extends through aplate member, it is necessary that the countersinking cutter A be guidedor axially aligned with the opening to assureY accurate countersinking.It is also desirable that the rate of feed of the countersinking cutterinto thev material, as well as the depth of the cut of saidcutter, becontrolled. 1n addition, the. member being countersunk should bereinforced or bracedon the side opposite that on which thecountersinking operation is being carried out. All of these factors,namely, supporting of the work piece, axial alignment of the` cutter andcontrol of the rate of feed and depth of cut, are essential to eicientand accurate countersinking.

For the purpose of guiding and axially aligning the cutter A withrespect to the opening C and also for the purpose of bracing or backingup the member being worked upon, a guide member and locking assembly isprovided. This assembly includes a tubular mandrel or member 31 which isadapted to project iorwardly of the cutter A in axial alignmenttherewith. The tubular mandrel or member 31 has an external diametersubstantially equal or slightly less than the opening C which is to becountersunk and its upper end is secured to a tubular rod 38 whichextends upwardly through an axial opening 3d which is formed in thecutter A and the shank 2l of said cutter. The upper end of the tubularrod 38 isthreaded into the bottom of an elongate piston rod 4I] and saidpiston rod extends upwardly through the bore lila of the drive shaft I8and also through an opening Mic formed axially of the partition I6 whichextends across the bottom of the cylinder I4. A suitable packing 4Ipacks on around the piston rod 40, and said rod is slidable axiallywithin the drive shaft; at the same time, the tubular connector 38 whichconnects the piston rod with the guide mandrel 31 is slidable throughthe cutter A.

The upper end of the piston rod 4t has connection with an outer piston42 which is reciprocable within the bore` I5 of the cylinder It. As isclearly shown in Figure 3 the piston l2 has an external diametersubstantially the same as the diameter of the bore l5 and has a suitablepacking ring 43 mountedin its external surface and engaging the wall ofthe 4bore of the cylinder. The piston ,42, is also formed with aninternal chamber 44 having a substantially flat bottom 45. The upper endof this chamber is closedI by a closure plate 46 which is secured bysuitable screws to the body portion of the piston. Within the upperportion of the chamber 4i an annular groove or recess 41 is provided inthe wall of said chamber. and this annular passage communicates with thebore of the cylinder below the piston through a plurality of inclinedpassages 4.8'. The purpose of the chamber 44, groove 41 and passages 48will be hereinafter described in detail.

From the foregoing, it will be seen that the countersinking cutter A ismounted within the housing and may be rotated through the drive pinion29 and drive gear 28 to impart a, rotation to the cutter. The guidemandrel 31 is connected directly with the `piston rod and with thepiston 42, and upon a relative movement of the piston with respect tothe housing the tubular guide mandrel or member 31 whichprojectsforwardly of the cutter A may undergo a longitudinal movementwith respect to the cutter and to the housing.

The tubular mandrel or member 31 is clearly shown in Figures 7 to 9 andis formed with an axial bore 49 extending entirely therethrough andcommunicating with the bore 38a of the tubular connecting element 38. Aradial opening 50 which is generally arcuate in cross-section is cut inthe wall of the mandrel or member 31, and a locking element 5| ismovable within this opening. The locking member 5| is shown in Figures 8and 9 and has an external surface formed on the same radius as theexternal surface of the mandrel. The locking member is secured withinthe opening 5U, as shown in Figure 7, by means of a spring wire 52 whichprojects upwardly through an opening 53 provided in the mandrel and theupper end of this wire is fastened within a recess 54 in the element.The spring wire 52 normally exerts its pressure to retain the lockingelement or block 5| in its inner position, and in such position theouter surface of the locking element forms a continuation of theexternal surface of the mandrel.

For moving the locking element or block 5| outwardly to the positionshown in Figure 8, the inner upper surface of the element or block isformed with an inclined surface 55 whichv is adapted to coact with thetapered lower end 56 of an actuator rod or bar 51. This actuator barextends axially through the bore 38a of the tubular -connector 38 andwhen said bar is in a raised position with respect to the lockingelement or block 5|, as illustrated in Figure 7, the block is in itsinner position, being held so by the spring wire 52. Upon a downwardmovement of the actuator rod 51 with respect to the locking element crblock 5|, the tapered lower end of the actuator coacts with the inclinedsurface 55 of the block to cause an outward swinging of the upper end ofsaid block to the position shown in Figure 8. This moves the outersurface of the upper portion of the locking element or block outwardlywith respect to the external surface of the guide mandrel 31 and therebyincreases the eiective external diameter of the mandrel at this point.The upper end of the locking element or block 5| may be inclined ortapered as indicated at 5 |a to facilitate the swinging movement.

In the operation of the guide mandrel 31 and the locking element 5|, themandrel is passed through the opening C in the member or work piece B soas to locate the locking element 5| on that side of the member B whichis opposite be countersunk. When located the actuator 51 is moved withrespect to the locking block, and this causes an outward swinging of theblock whereby the upper end 5| a of the locking block abuts or isadjacent to the surface of the work piece or member B. So long as thelocking block or element 5| remains in an expanded position `innerpiston 58 it will be evident that a retraction of the mandrel throughthe opening C is prevented. This locking of the mandrel 31 to the memberor work piece B axially aligns and maintains the align ment of thecutter A with the opening C. Also, because the upper surface 5| a of thelocking element 5| is arcuate, the blocl presents an amplined surfacewhich contacts the member B and functions as a backing or support whenthe subsequent countersinking operation begins.

For controlling the operation of the actuator rod 51 an inner piston 58is provided. This piston is connected through a piston rod 59 with theupper end of the actuator rod 51 which rod extends axially from theupper end of the tubular connector 38 and into the bore 40a of the outerpiston rod. The inner piston 58 is mounted to undergo limited movementwithin the chamber 44 of the outer piston 42 and is, of course, providedwith an external packing ring 68.. The upper portion of the piston rod59 is bored out as indicated at 6|, and a tubular conductor 62 has itslower portion extending into this bore. The upper portion of theconductor 62 is suitably secured in a xed position within an opening 63in the cover plate I1 of the cylinder. The tubular conductor extendsthrough an axial opening 46a in the cover plate 46 of the outer piston42, downwardly through the chamber 44 and through a collar 64 secured inthe upper end of the bore 6| of the inner piston 58 and its rod 59. Theextreme lower end of the conductor 62 has a stop collar |55 threadedthereon and this collar is adapted to be engaged by the collar 64 whichis carried by the inner piston, as will be explained.

The tubular` conductor 62 has a bore 66 having an open lower endcommunicating with the lower portion of the bore 6| of the inner pistonrod 59. The upper end of the bore 66 communicates with an angularpassage 61 which extends through the cover plate |1 and the wall of thecylinder |4. The other end of the passage 61 is connected through acontrol valve 68 having a suitable hand control lever 69, and said valvecontrols the admission of air under pressure from an air line 10 whichis, of course, suitably connected to the valve. When the valve 68 is ina position permitting ow of air from the conduit 10 to the passage 61,air under pressure flows through the passage and then downwardly of thetubular conductor 62 and into the bore 6| of the inner piston rod 59.From this point the air under pressure passes the stop collar 65 throughexternal recesses 65a provided in said collar and flows upward-ly ithrough the bore 6|. From the bore this air under pressure passesthrough an inclined port 1| which is provided in the inner piston 58,and thus, air is conducted into the chamber. If the spect to the outerpiston 42, as illustrated. in Figure 4, this air under pressure will actupon the inner piston in the space;v between said inner piston and thecover plate 48 and will function to move the inner piston 58 downwardlyrelative to the outer piston 42, whereby the annular groove 41 in theupper portion of the chamber is uncovered. The downward movement of thewith respect to the outer piston 42 results in a longitudinal movementof the actuator rod 51 piston relative to the locking block 5|. which iscarried by the guide mandrel-31; the guide mandrel 31 is secured throughthe connector 38 with which has connection with the inner' Y. the sidevwhich is to be countersunk.

the-outerl piston -rod 40, and fit is thusl obvious that the initialmovement lof the inner piston. downwardly in the lchamber' relative tothe outer piston will cause an expansion` of the locking element l.

Following the relative movement o the inner piston 58 with respect tothe outer piston 42, the uncovering of the groove 41 within4 the chamber44 will rperm-it air under pressure to pass downe wardly through theports 48 into the bore o the cylinder between the outer piston i2 andthe partition i6 which closes the end of the cylinder. This air underpressure will tend to move the outer piston 42 toward the cover plate l1but since the outer piston yis directly connected through the piston rod4i) orrconnector 3% with the mandrel 31 which is locked againstwithdrawal through the opening by the locking block, the outer piston isimmovable. The admission of the air into the space between the piston s2and the` partition It will therefore result in forcing the cylinder i4and the entire housing assembly downwardly with respect to the outerpiston. Because the Lcountersinlring cutter A is directly mounted in andforms a part oi the housing, the admission oi air below the outer piston42 will move the cutter downwardly into contact with the plate or memberB. .es the housing is moved in a direction toward the plate member or.work piece B the area between the outer piston 42 and the cover platel? of the cylinder is vented through an angular opening 12 which extendsvfrom the'upper end oi the bore of theA cylinder I4 to the air controlvalve tt.

From the foregoing, it will be evident that the guide mandrel 31 isfirst engaged through the opening C which is to be countersunk and thelocking element or block 5| is then actuated to engage that side of themember which is opposite At this time, the cutter A is spaced upwardlyfrom thev opening. As explained, the locking block is expanded by themovement of the inner piston relative to the outer piston and thereafterthe air is introduced into the space between thel outer piston and theend partition It of the cylinder. rlhe introduction of air into thisarea functions to move the entire housing which carries the cutterdownwardly into engagement with the member to be countersunk, and atthis point the control. lever 3G which controls the rotative movement ofthe countersinking cutter is actuated to impart rotation to the cutter.As will hereinafter appear the feed of the cutter conu tinucs while thecutter is. rotating to control the depth to which the countersinkingoperation will extend. Also, as will be explained, the rate oi feed ofthe countersinlring cutter is controlled as the opening C is.countersunls.

For controlling the rate of feed o the cutter A to the work and also forcontrolling the depth of the countersinking out, as well as formaintaining true .axial alignment of the cutter throughout theoperation, anr aligning and control assembly generally indicated at D ispro-` vided on the lower end of the housing I0. The assembly D includesa generally cylindrical shaped body 15 which has an axial opening 'itsurrounding the sleeve member 22 which; as explainedis bolted to thelower portion of the housing l0. The lower portion of the body has atrio of extended portions which provide downwar-diy din'ected extensionsor ffoot pieces 11. Alighd with each extension' 'ol' foot .piece 1.1 is'a' (zyliimier 18 formed. in the'body and extending' of cach cylinder isclosed by;A a closureV plate 19 threaded into the cylinder 18. Eachcylinder has apiston therein and this piston is supported by a pstonrod8l which is secured to the extended annularl ange 23 of the sleevemember 22 (Figure 3). The lower end of each piston hasla guide rod 82which projects through an axial opening 83 in each extension or footpiece 11. Suitable packing rings 84 and 85 seal oil around the guide rod82 and the piston supporting rod, 8l'. For normally urging the body 15and the foot pieces 11 which form a part thereof downwardly with respectto the housing Il] a plurality of coil springs 86 are disposed be- 'ytween the lower end of the housing and the body., it being preferablethat each spring be retained within a recess 81 in the body.

The upper ends vof the cylinders 18 are connected by passages 88 and89,` while the lower ends of the cylinders are connected by passages dand 9| (Figure 16). The passages 83 and 89 have connection through avertical passage Sila'. in which a metering valve S2 is mounted. Themetering valve is disposed within a lateral opening S3 provided in thewall ofthe body 15, and the adjustmentof this valve will control theflow of fluid thereby. IThe passages 39 and 9| are connected by avertical passage 94 which is provided with a spring-pressed check valveQ5.

The three cylinders 18 are completely filled with hydraulic fluid which,of course, is present on both sides of the pistons Sii. The coil springsSt 'are normally urging the body 1,5 having the ioot pieces 11 in adirection away from the body ifi, which means that the foot pieces 11are in an extended position with the pistons 3s] in the upper portionsof their` respective cylinders 18. Extension of the body 15 and completedisplacementtherefrom is limited by an elongate headed bolt Qt (Figure13) which extends through a counterbored passage tta in the body 15 andwhich is threaded into an opening S1 provided in the lower end oi thehousing It. When the foot pieces 11 are engaged with the work or platemember B and air pressure is applied to move the housing downwardly, adownward force is applied to each of the pistons 8B since these pistonsare secured to the housing. Since each piston is movable within one ofthe cylinders 18 it will be apparent that the downward force on thehousing will tend to cause an inward movement of the body 15 whichcarries the foot pieces inwardly of the housing. The rate of movement ofthe foot pieces and body will, of course, be controlled by the by-.passor the hy. draulic fluid from below the pistons 8B through the passagesand 9|, and then through the vertical passage 90a to the upperv passages83 and 89. Since the metering valve $2 is mounted inthe vertical passageStd it is evident that the rate of ilow lay-passing from the lower endof each piston to its upper end is controlled. Thus, the rate ofmovement of the foot pieces 1i and body v15 inwardly of the housing iscontrolled; and this in turn controls the rate oi feed ci the cutter Ainto the work. AIt is also noted that because the foot pieces arelocated equidistant around the cutter they provide three points ofcontact with the Work piece which assures the maintenance of accuratealignment of the cutter with the opening.

Upon retraction or disengagement 'of the cutter from the wrk'after thecountersinking operation. is complete the springs 86 will again move thedownwardly from its `upper end. `The upper end-75 body ,l'a'nd theV footpieces outwardly of the housing I and in order to permit a fairly rapidmovement in this direction the check valve 95 in the vertical passage 94opens, which allowsa fairly rapid flow from the upper passages 8B and 89downwardly through the passage 94 past this check valve and intopassages 9|) and 9| which extend to the lower end of the cylinders 18.

For controlling the amount of movement of the body 15 and foot pieces 11inwardly of the housing to thereby control the depth of the cut made bythe countersinking tool A, an adjusting collar 98 is threaded onto thelower end of the housing. This collar is provided with an inwardlydirected annular flange 99 which is adapted to be engaged by an annularshoulder lill formed on the body 15. It will be evident that by rotatingthe stop or limiting collar 98 the amount of inward movement of the footpieces 1l with respect to the housing upon downward movement of thehousing is controlled. In order to lock the limiting or stop collar 98in its adjusted position a serrated lock ring |0| is slidably mounted onpins |ll2 on the lower end of the body, and this ring is constantlyurged toward the stop collar by a coil spring |93. The lower edge of thelock ring is serrated at |04 (Figure 6) and these serrations are adaptedto engage serrations |05 provided on the upper edge of the stop orlimiting collar to thereby lock said collar in adjusted positions.

The operation of the device is believed obvious from the foregoing.Initially the parts are in the position shown in Figure l in whichposition the aligning and control assembly D has its foot piecesextended with respect to the housing i9, being urged to this position bythe coil springs B6. The duplex piston arrangement comprising the outerpiston 42 and the inner piston 58 is in the position shown in Figures 1and Ll, and in such position the actuator rod 51 is raised with respectto the locking element or block 5|. The outer piston 42 is nearer theclosed end or partition It of the cylinder.

The operator engages the extending guide mandrel 31 with the opening Cin the plate member B so as to locate the locking block 5| on that sideof the member which is opposite the side to be countersunk. The aircontrol valve 58 is then operated by its control lever 69 to direct airunder pressure from the conduit through the angular passage 61,downwardly through the tubular conductor 62, then through the bore 6|and passage 1| into the upper end of the chamber 44. This air underpressure will act upon the inner and outer pistons in a manner to movethe inner piston 58 from its position in Figure 4 covering the annulargroove 41 to the position shown in Figure 3. This movement of the pistonmoves the actuator rod 51 with respect to the locking block 5| to swingthe locking block outwardly and thereafter prevent retraction of theguide mandrel 31 from the opening C.

As the annular groove 41 is uncovered due to the movement of the innerpiston 58 with respect to the outer piston 42, the air under pressure isdirected through passages 48 in the outer piston into the space betweenthe outer piston and the end partition |6 of the cylinder. This airtends to move the piston 42 upwardly but since the outer piston is.directly connected to the mandrel which has been locked againstdisplacement from the opening C the air pressure functions to move theentire housing assembly downwardly with respect to the stationary pistonassembly.

As the housing assembly moves downwardly ,the cutter A 4Whix'shis`attached.thereto is fed mounted for limited movement with thereto andtoward the closed end portion ,thereof downwardly to the plate member Band the rate of movement is controlled by the metering valve 92 in thehydraulic system of the assembly D. As the cutter A moves into contactwith the work the operating lever 36 (Figure 2) is actuated to impart arotation to the drive shaft I8 and to the cutter. The air pressureacting .against the housing continues to urge the cutter into the workand the rate of feed is continued to be controlled by the movement of hebody 15 as controlled by the hydraulic system. The countersinkingoperation continues until the shoulder |00 on the body 15 of theassembly D strikes the inwardly directed ange 99 of the stop or limitingcollar which has been previously adjusted. At this point further inwardmovement of the cutter A with respect to the member B is halted and thusthe depth of the countersinking operation is accurately controlled.

At this time, rotation of the cutter A is halted and the air valve 68 ismoved to its opposite position which vents the passage 61 to atmosphereand directs air under pressure to the passage 12 into the space betweenthe outer piston 42 and the cover plate |1. This air pressure results ina relative movement between the housing and the piston 42 which causesthe piston to move toward the end partition I6. As the piston approachesthe partition and reaches the position shown in Figure 5 the collar 64within the inner piston 58 engages the stop collar 65 on the tubularconductor 62 to stop the simultaneous travel of the inner piston withrespect to the outer piston. Continued movement of the outer piston. 42within the cylinder results in the inner piston again returning to theposition shown in Figure 4. Such relative movement of the two pistonscauses a retraction of the locking block 5| because the actuator bar 51moves upwardly relative: thereto. The parts have thus returned to theiroriginal position, the air control valve 68 is closed, and the device isready for the next operation.

From the foregoing, it will be seen that an apparatus is provided whichwill eiectively align the countersinking tool, maintain such alignmentand control the rate of feed as well as the depth of the countersinkingcut. The locking of the guide mandrel to the plate provides for backingup the plate on the side opposite that on which the countersinking iseffected.

The foregoing disclosure and description of the invention isillustrative and explanatory thereof spirit of the invention. i

Having described the invention, l claim:

1. A countersinking apparatus for countersinking an opening extendingthrough a work piece and including a housing, a countersinking cutterrotatably mounted on the lower portion of the housing, a hollowcylindrical guide member having an axially closed end portion extendingaxi-` ally of the cutter in advance thereof and adapted to projectthrough the opening in the work piece,- a latch mounted in the side ofthe guide member near the closed end portion thereof and engageable withthat side of the work piece opposite the side to be countersunk forlocking the guide mem'l ber against withdrawal from the opening, and anactuator in the interior of said guide member respect for actuating saidlatch into locking position.

e cou 'tersi'nking ani'ofratus for counter'slink# 4 v'g' Yeit'e'nd'ing'through a, Work piece a housing, arotatab-le counter- "f cutterymounted on the lo'vvei,1 portion of the yusing, guide member extendingaxially in advaneeof the cutter and aldallfd to project t@ h theopeningv rhefwork piece, locking kr'r'ioii'n teri on the guide memberand` enablev vith 4that side of the vvori piece oppot theside to becountersunklior lockingv the anbei: against Withdrawal from the open'- ial'g'n'ing assembly mounted onk thev loyver ffthefhousinfafor engagingthe Work maintain axial alignment of the counterrespect to the openingbeing Ainfor/ernent of the cutter 'into l e th `or'l'piece,'saidali'g'ning assiemiy, meid-ding 'a 'piu iity or hydraulic cyun ershaving .pisto there1n, and 'means for Vcon e olf 'ss f'nverauiic uuidaround said i'oli wie Gf movement f the 12d 'cutter nto Contact -Witlfithe Work @King ennemies' es Set forth i111 adjustable 'Strip meer? f0.1'e tf'thgehsretlisCylinders g assernblf,V

o t en "the ijwer 'portieri of trie 1de 'member extending axially'nomine witnene end y nadvaneegoithej ne este' ing. into the ee 'certesm ans suldcfinember plat tiatorf V t )A respee'tto the piston' securedto the guidernern bei' and also wherein the position ofthe pistonseuriedfto the actuator witnrespectito the piston of the guide membercontrolsv the direction of movement ofthe housing relative to the guidemember.

apparatus. Yas set forth in claim4, togather with means for controllingthe rate of movement. of; the housingwith respect to the guide membervwhen rncvementv is imparted toy said monsite.

Tenn apparatus as,l set forth in claim 4, togetheriwith'ajcenteringassembly mounted on the lower portion of` the, housing, andincluding, a pluralityfoflmovable cylinders spaced around. thecutterxvith, the lowerends of said cylinders en'- gageable, withtheyeleme'nt. through which the peningtozbe countersunk extends, andhydraulic means. fory controlling the movement of. saidcylinderstofthereby. control therate of movement ofthfoutter withrespect to the elementi gthei.- `lilith a oiitiing' assembly mounted onthe lower portion of the housing and including, 'a plurality of movablecylinders spaced around the cutterwith the lower ends oi said cylindersengageable with the element through which the opening to be countersunkextends, hydraulic means for'oontrolling'the movementvof said cylindersto thereby control the rate of movement of the cutter with respect tothe element,- and means mounted on the housing and coacting with themovable cylinders for limiting the extent vof movement of saidcylinders. e

9. An apparatusv for countersinking an opening extending through a nat`plate and includine,A a housing, a counter'sinking cutter mounted on thelower portion of the housing, a, guidev member extending axially inadvance of the cutter and adapted to project through the opening, in theWork piece, means on the guide member for'lo'ck# ing said member'against withdrawal from the opening, a cylinder Within the housingliar/iii?,f the guide member extending thelento, a piston secured to theend of the guide member Within the cylinder,v and means for introducingpressure huid Within the cylinder between one end of the cylinderand'one side of the piston, whereby. the piston is held stationary.through themean@l l'oclgf ing the guide member Ato the plate tqtherebyeil,- iect a movement 0f the housing- 'W'ithl respeett the snide member@ad to, the., plate to, more 'th mittel" iet@ @easement withilse-Platele fm. termine es Se.. ione., 9., i9.- tetherl with mentallyGerlirellesfmeens for re:- tatirig the cutter after it engagestheplateniemr ber to perform a vcountersinlfring operation.r

ll. apparatus assetiorth in claim 9, tojgether with manually controlled;means for EQ;- tating the cutter after it engages the plate mem,"- berto perform a countersinlring operation, and meansY for reversing theapplicationfof pressllle nuid within the cylinder to, eiectmovement ofthe housing with respect to, the 'guide member in an opposite directionto. disengagethe Vcutter from theplate.

12. An apparatus as, setforth in `claim 9, to;- gether with 4meansmounted 'on the housing for controlling the. rate of movement of thehousing with respect to. the guide 'member andiplate.

An apparatus. 'asfset forth inA claim `9,`to gethere with means mountedon the. housing for controllingthe rate of movenfi'entY of "the .housingwithrespect to the guide member-and plate, and adjustable means forlimiting the movement "of the housing with respect to the guide-memberand piste to thereby control 'the-depth of the cutl made bythecountersinlring cutter.'

14. A eounter'snking apparatus 'i-or counter# sinking en openingextending through e 'wrk piece and including a housing, a` rotatablec'ounte'rsinkmg cutter' mounted on the lower `por-- tionN-ofthe housing,a locking membereiztiiding' aiellyii advance, 0f, the einer and;adapted. to project throughthen'pe ing in` the 'Work piece et;iviththatsidef Qi 'the Wrth, Diese @retirs fr. linking drawalfigoin fSeidholisine ,harm

e bravest@ hydra ,is

., Pisten., w enirol, the raie 'of ovement of the housing' andY cutter'intoY ccn-y tact Witht-hevvorli piece.

l5.` Av 'counter'sinking apparatiis for counter- 'siikingfen openingeX-tending through! wo-l Pisten, therein be t resets., for) @ont fluid'around i' piece and including a housing, a countersinking axially insaid guide member and mounted for cutter rotatably mounted on the lowerportion of limited movement with respect thereto for movthe housing, ahollow cylindrical guide member ing said latch outwardly.

having a closed end extending axially of theA cut- SHROPSHIRE E. REES.ter in advance thereof and adapted to project J through the opening ofthe Work piece, a radial Referens Cited in the me f this patent Openingin the wall of said guide member ad- UNITED STATES PATENTS ,jacentl theclosed end thereof, a latch mounted Number Name a Date 1n said openingmovable outwardly for engage- 1 964 023 Armstrong une 26 193,1 ment withthat side of the work piece opposite 10 2'466'745 Seamans Apr 12 1949the side to be countersunk for locking the guide 2479660 Wright n Aug'23' 1949 member against withdrawal from the opening, spring meansfastening said latch to said guide FOREIGN PATENTS member and normallymaintaining the latch in- Number Country Date wardly into inoperativeposition, and an actuator 15 648,221 Germany July 26, 1937

